Deeper than Knee Deep

New Mexico's Carlsbad Caverns is famous for its bats. And while the bats there deserve attention, the deposits these animals leave behind are also impressive.

The bats, Brazilian Free-tailed Bats, have inhabited the caverns for many thousands of years. Their population, once several million, is now less than one million. Yet the bats continue to attract tourists and make new contributions to the valuable resource below them.

The resource, of course, is bat guano, which in some areas within Carlsbad Caverns is nearly 50 feet deep. There's so much of it, in fact, that special guano mines exist to excavate the stuff. And what is it used for? In the past it provided a key ingredient in gunpowder and fertilized crops. Now enzymes from bacteria that live exclusively in bat guano appear in laundry detergents, antibiotics, and other products.